This invention relates to a seat belt buckle having an electrical switch therein for operation by the insertion of a tongue plate or D-ring into operative connection with the belt buckle.
The switch within the seat belt buckle is for the purposes of controlling electrical circuits which indicate whether or not a seat belt has been buckled by a vehicle occupant. Typically, a warning buzzer circuit is actuated if a vehicle is started without the safety belt being buckled.
Some safety belt buckles with switches therein have been used commercially in automobiles. Other safety belt buckle switches have been proposed and have failed because they were either too expensive or failed to meet the auto manufacturer's specifications or federal government's safety regulations. It will be appreciated that safety belt buckles are subjected to severe reliability and environmental tests as they may be used in extremely hot or cold temperatures and in dirty and dusty environments or in hot and humid environments. The hot and humid environments tend to cause corrosion whereas the dirt and dust tend to prevent operation particularly of switches. Moreover, the lead wire connections to the buckle switches must be sufficiently strong to withstand pull tests and flexural tests. Switches for seat belts must have a relatively high cycle life in that they may be used frequently over a long life for a vehicle with little care. Preferably, the switch should be small to be incorporated into the buckle. Also, it should be constructed with relatively few inexpensive parts and avoid costly assembly techniques such as used in threaded nuts and bolts or rivets.
Accordingly, a general object of the present invention is to provide a new and improved, as contrasted to the prior art, safety belt buckle having a switch therein.